It wasn't Michael Gove, David Blunkett or even Kenneth Baker who first whipped up a fuss about "informal methods of teaching", and suggested a restored emphasis on the three Rs. No, it was prime minister James Callaghan, in a speech at Ruskin College in 1976. For four decades England has fretted about falling behind in the educational basics. And throughout those four decades, a thumping great OECD report concluded on Tuesday, far from the problem having been righted, England has increasingly had a real problem to worry about.

Out of 24 nations, English young adults now rank 22nd for literacy and 21st for numeracy, which sounds bad enough, but the sinister twist is how things have got worse as the years go by. In most wealthy countries, the expectation is that each generation will always be better-schooled than the last; improving GCSE results and rising university enrolment implied England fitted the pattern. The new data suggests that these things may have been statistical mirages. The over-55s proved better than the youngsters with numbers and letters alike which means, as the international thinktank bluntly put it, "England is the only country where the oldest age group has higher proficiency in both literacy and numeracy than the youngest group".

There is often controversy with learning league tables – rankings skip around, depending on how one country's high school diploma is compared to another's general certificate. The OECD's analysis, however, is less susceptible to reassuring rationalisation. It was based on tests taken by 166,000 adults, tailor-made to allow for cross-border comparisons. Of course, a narrow focus on literary and numeracy does not cover the breadth of a rich education. England's schools do many things better than they did in the days of chalk, talk and the cane. Education in Japan, which topped many of the tables, is often criticised for discouraging lateral thought. On the other hand, there is a definite correlation between the OECD's narrow educational metrics and productivity growth: if you care about the economy, you need to worry about the three Rs too.

A real problem, then, but what to do about it? After all, children in England (Scotland and Wales have separate education policies, and were not in the data) have already been subjected to decades of bright ideas from Whitehall, each of which was sold as the way to root out innumeracy and illiteracy. The national curriculum, SATs, exams, then coursework, then exams again – all have been offered up as solutions; none has done the trick. New Labour's "literacy hour" was, on the face of it, targeted with precision but, as Conservative ministers gleefully pointed out on Tuesday, the young adults facing problems with reading and writing today were Tony Blair's children. It would, however, be rash to assume that Mr Gove's enthusiasm for overhauling governance structures will necessarily do the trick either. There is scant evidence, and still less any real theory, as to why this should succeed where every previous bright idea has failed.

A more solid approach would start by asking which pupils are falling behind: the OECD found that the link between less-educated homes and pupil's educational problems was almost twice as strong in England as in some other countries. Various targeted interventions had just started to erode the old cast-iron link between social class and classroom performance by the time Labour lost power, and the Liberal Democrats' valuable, if overhyped, pupil premium should allow further progress.

The difficulty, however, is that child poverty is about to rocket, owing chiefly to benefit cutbacks. Every teacher knows that the way things are going at home has a bearing on concentration in the classroom. For a third of a century, England's poor communities have been left behind, and among other things the OECD has captured some of the consequences. Of course it is what goes on in the classroom that matters, but that depends on life beyond school walls as much as any Whitehall wheeze.